Any body text can have an image added to it or a pdf or url linked. To add an image, or a pdf, is a two part process. First the file needs to be uploaded to server from your computer. The second part is inserting the image or link.
First, to review, that body text is sometimes called different things in different places. In Biblio the body text is typically going to be in Full Text though the imported articles are mostly in Notes. In bios the body text is called Bio and in events it is called Event Description.
Body text will typically have a wysiwyg editor. Any time you need to edit HTML you need to switch the editor to the Source mode. Here you will not use Source mode. The wysiwyg editor will create html source code for you.
When you want to add an pdf or url link first type out the text that you want to link from. This can be the url or pdf name or anything like: "click here to download the pdf". Then select the exact text you wan to link from. This might be the whole line or just the word "here" in the last example. Once the text you want to link from is selected click on the link button. This is the button that looks like a pair of binoculars over a globe, at least that what is looks like to me. It is on the bottom row and is the fist button of a group of three, in the middle group.
After clicking this button a window will open. In either a url link of a link to a local pdf, change the link type to URL. Now a browse server button will appear.
If you just want make a url link to another site make sure the protocal is set to http:// or another appropriate protocal and type the url in the url field then hit OK.
If you want to add a pdf with a link then click on Browse Server button. This will open another larger window. On the left side of this window is navigation for the server's file tree and begins with sites/default/files/. If you are adding a pdf to a biblio content type it will by definition be a history article and you need to navigate to the history/pdf folder (sites/default/files/history/pdf but all you see is history/pdf). You should see the pdfs already in the pdf folder on the right side of the window. Again this is as David designed it on the last site and I have kept things the same. I believe all history pdfs are in this folder.
If the pdf is already on the server, select the pdf and then select Insert File. The larger window will close and you will see the path to the pdf appear in the smaller window. Select OK and you are done.
If the pdf is not already up on the server and you want to upload a new one, still in the selected directory, click on Upload (the button on the top left of the window).
Use the browse button to browse your machine for the pdf to upload. When the file is selected click on Upload in the rectangle at the bottom left of the browse box. Doing so will upload a copy of the file to the server with the same name as it as on your hard drive. Though you can select the name I don't yet see a way to edit it in this interface so be sure to name it the way you want it first.
Once uploaded the name will appear in the list for the selected folder on the right side of the window. Select the newly uploaded file and then click Insert File (the button with the grean check on the top of the window at the far right).
Again, at this point the larger window will disappear and the path for the selected pdf will appear in the url field of the link window. Hit OK and you are done.
Be sure to save your changes for the page when done editing the body text or the changes will be lost.